Retractable landing gear for model planes



July 21, 1953 E. s. COOK RETRACTABLE LANDING GEAR FOR MODEL PLANES Filed Oct. 21

[066R 5. COOK INVENTOR.

Patented July 21, 1953 NT, OFFICE.

RETRACTABLE LANDING GEAR FOR.

a MODEL PLANES sugars; Cook, Redlands', cam; j 'Application'octoberill, 1949, Serial-No.-1 22, 705

'lClaims. (01.46-77) The present invention relates to retractable landing gear structures for model airplanes In building model airplanes, an attempt is made to simulate as close as possible the structure of the plane from which the model airplane is copied. This is particularly desirable so far as the retractable landing gear is concerned, since the provision of the landing gear not only makes the model plane more closely resemble the plane from which it is copied, but thelanding gear serves also, in the case of the model airplane, to allow it to ily faster thanwould otherwise be the case, and of still greater importance to allow the model airplane to land Without damage.

It is therefore an object of the present inven-,

tion to provide a retractable landing gear for model planes, characterized by its simplicity, its ease of manufacture and assembly, and inexpensiveness for the intended purpose.

Another object of the present invention is to provide an improved retractable landing gear having the desirable features mentioned in the previous object, arranged so that the landing gear maybe operated from the ground.

Another object of the present invention is to provide an improved landing gear for model planes which includes a mechanism assuring a stable locked position of the landing gear either when the landing gear is extended or when the landing gear is retracted.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. This invention itself, both as to its organization and manner of operation, together with further objects and advantages thereof, maybe best understood by reference to the following description taken in connection with the accompanying drawings in which: Figure 1 is a top plan view of a model airplane embodying features of the present invention, I Figure 2 is a longitudinal sectional view taken substantially on the line 22 of Figure 1,

Figure 2A is a longitudinal sectional view similar to the view shown in Figure2but with the parts shown in the position they" assume when the gear is in retracted position instead of the fully extended position as shown in Figure 2,

Figures 3 and 4 are sectionalfviews taken on 7 corresponding lines 3-3 and'44 in Figure 2,

Figure 5 is an enlargedview' of some of the linkage shown in Figure 2, and

Figure 6 is a view taken substantially on line 6-6 of Figure 1..

It is the customary practice in flying model airplanes to provide a pair of strings or cords extending from. the plane and connected to a U-shaped han le grasped by an individual and movable in-different relative positions to maneuver the aircraft; and, in such case, the other ends of the strin'gs or cords are attached to operateth'eeleva'tors in accordance with movement of the l ly-shaped handle, all in accordance with conventional mechanism and practice. I In accordance with the present. invention, it is proposed to 'a'dd'a third string or control wire ID for actuating the retractable landing gear either to a retracted position orto an extended position, The apparatus described herein for accomplishing this purpose is operated by asingle tug on the control wire 19 in this manner:

Assuming that the landing gear is in a fully retracted position, a tug onthe control wire I 0 releases a spring operated mechanism which thereafter functions to move thelanding gear to the fully extended position. When such gear reaches its fully extended position it is automatisition, the control wire I0 is again tugged to' cause the spring in the mechanism to move the gear to its retracted position; and, when such gear reaches its fully retracted position it is automatically locked in-such retracted position.

, Thus, the mechanismis locked either in its retracted position or in its extended position, the locking being produced by the position assumed by the rods I I 13, I213 with respect to the rotatable crankshaft.- One of the overcentered positions is clearly shown in Figure 6, it being observed that any forces transmitted kto'the wheels I I, 12 are incapable of producing 'rotative movement of the crankshaft to I which such wheels 1 are pivoted. Again, in the retracted'position of the'wheels l l, 12, the crankshaft jl8"assum'es a position de greesjfrom the position shown in Figure 6, as shown in Figure 2A, to again move the rods llB, I2B ma different position pasta dead center po sition wherein gravity forces acting on the wheels and-strut's'are' incapable of causing ro tation of thecranksh'aft.

I For accomplishing the abovefunction, the arrangernent described in detail hereinafter is pro- (The landing "gear mechanism includes three landing wheels; namely, a pair of wheels H, l2 disposed underjthe wing l5 of the plane'and retractable therein, and-a, tail wheel l 3 movable fuselage.

3 into a retracted position within the fuselage I8 of the plane. The wheels II, I2 are rotatably mounted on one end of their respective struts I IA, I2A, the other end of such struts IIA, I2A being bent as shown in Figure 1, and being pivoted to one end of corresponding rods IIB, I2B, with the other end of such rods IIB, I2B pivotally connected to the .rotatable crank shaft I3, as shown in Figure 5. An intermediate portion of such struts IIA, I2A is journaled for rotation in the bearings I ID, I 2D mounted on the wings and internally thereof.

The crank shaft I8 is rotatably supported in spaced bearings provided where such shaft extends through the walls of the housing III, which is mounted on the fuselage IIi of theplane. This shaft I8 is continuously rotatable only one direction, and is rotated by the energy supplied from the prestressed torque spring I9, having its inner end attached to the shaft I8 as .shown in Figure 4, and its outer end attached to the spring housing 20 rotatablymounted with respect to the The spring 13 is prestressed .or wound upon using a screw driver to turn the winding knob 21, having a screw driver s'lot'22 therein and iournaled for rotation in the housing 23. The lower end of this knob 2| carries a bevel gear 24 engageable with a corresponding bevel gear 25 stationarily mounted on the spring housing '20, all of which is rotatable on shaft I8. The spur gear 21E cooperating with the pawl 21F allows rotation of the shaft I8 only in one direction.

After the spring I8 is wound or prestressed, upon turning the winding knob 2I, the torque spring I8 is prevented from unwinding by an escapement mechanism .28, shown more clearly in Figure 3. This escapement mechanism 28 includes a cam locking member '21 which is mounted on the shaft I8 and normally engaged by the spring pressed pivoted dog 28. The dog 28 is pivotally mounted on the housing .23 by the pin 29, and is normally biased into engagement with the cam lock 21 by the coiltension spring 38, having one of its ends abutting the casing 23 and the other one .of its ends abutting the dog 28. This dog 28 may be moved out of engagement with the cam lock 21 to allow the shaft I8 to rotate upon pulling the string or control cord to the left in Figure 3.

It is observed that the cam'lock 21 is provided with two flat surfaces 21A, 21B disposed 180 degrees apart and engageable by the dog member 28. Thus, it is observed that upon each tug or pull on the control cable III to the leftin Figure 3, an immediate release of the tension on cable or wire I II results in rotation of the shaft I8 through substantially 180 degrees.

The landing gear is extended during the first 180 degrees of rotation of shaft I8 and is then retracted upon the following 180 degrees rotation of the shaft I8 in the same direction.

In order to control the movement of shaft I8 under the influence of the torque supplied by the torque spring I8, there is preferably provided a damper 32 comprising a fluid piston cylinder arrangement, with the cylinder 33 stationarily mounted on the fuselage and with the piston 34 within the cylinder connected with the crank arm I8A on shaft I8. The piston 34 may have a metering aperture therethrough or may be made undersize with respect to the bar of the cylinder 33, so that the flow of viscous liquid in the cylinder 33 controls the rate at which the shaft I8 rotates. The provision of this damper 32 serves to make the speed of the shaft I8 substantially 4 the same, as the tension in the prestressed spring I8 is being relieved.

Further, rotation of the shaft I8 results in movement of the flaps 35, 38, which are hinged on the corresponding rods 35A, 38A, the outer ends of which are journaled for rotation in the wings, and the inner ends of which are bent to form a general V-shape, as shown in Figure 1, and are attached through the link 31 to the link arm I8B of shaft l8. The link 31 is rotatably mounted on an arm I8B.

The tail Wheel I3 is also connected to the crank .strut I3A thrust rod 40, pivoted bell crank 4| and the thrust rod 42. The strut I3A is pivoted at appoint intermediate its ends on the pivot pin 44, mounted in the fuselage, with the upper end of such strut I3A pin connected to one end of thrust rod 40, the other end of thrust rod 48 being pin connected to one arm of the bell crank lever "4| pivoted on the pin 41 stationarily mounted with respect to the fuselage. The other arm of the bell crank H is pin connected to the upper end of the thrust rod 42, having its lower end pivoted on the crank I8B. By this connection, it observed that wheel I3 is movable from a retracted position within the fuselage to an extended position and then back to a retracted position upon full 360 degrees rotation of the shaft I8. The pin connection between the thrust rod 42 and bell crank H is sufficiently sloppy" to prevent binding in the motion transfer mechanism described above when crank arm I813 rotates, i. e., the thrust rod 42 is movable not only in the plane of the bell crank H but may move laterally of such plane a limited amount to prevent binding.

It is observed further that when the landing gear is extended the arm 38A and corresponding arm 35A (Figure 2) are in their downward position, to cause the flaps 35, 36 to be lowered to reduce the speed of the plane in landing.

It is thus observed that there is provided a tricycle landing gear which operates jointly with means to move the flap to a landing or a flying position.

While I have described my invention incorporated in an airplane adapted to be controlled by elongated control cables, it is apparent that certain features of the present invention may be practiced without the necessity of using such control cables.

While the particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

I claim:

1. In an aircraft control of the character described, a landing wheel rotatably mounted on a strut, said strut being pivoted on said aircraft, a crank connected to said strut, a prestressed spring connected to said crank to rotate said crank continuously in one direction, an escapement mechanism having an element connected to said crank and normally preventing rotation of said crank, said escapement mechanism comprising a cam with a pair of teeth thereon displaced degrees rotating with said crank and a spring pressed dog normally engaging said toothed cam to prevent rotation thereof, and a control cable extending from said aircraft and attached to said dog to move said dog to allow rotation of said crank and resulting movement of said landing wheel.

2. In an aircraft control of the character described, a landing wheel rotatably mounted on a strut, said strut being pivoted on said aircraft, a

crank connected to said strut, a prestressed spring connected to said crank to rotate said crank continuously in one direction, an escapement mechanism comprising a cam with a pair of teeth thereon displaced 180 degrees connected to said crank and rotating with said crank, a spring pressed dog normally engaging said toothed cam to prevent rotation thereof, a control cable extending from said aircraft and attached to said dog to move said dog to allow rotation of said crank and resulting movement of saidlanding wheel, and a flap pivoted on said aircraft, and means connecting said crank to said flap for movement thereby.

3. The invention defined in claim 1, characterized by the incorporation with the structure set forth therein, of a fluid cylinder containing a viscous fluid and a relatively movable piston, and a connection between said crank and said piston to control the movement of said crank.

4. The invention defined in claim 2 characterized by the incorporation with the structure set forth therein, of a tail wheel, a strut carrying said tail wheel andpivoted to said aircraft, and a connection between said strut and said crank to move said tail wheel with said crank.

5. In an aircraft control of the character described, a casing mounted on said aircraft and rotatably supporting a crank shaft, a torque spring mounted within said casing with its axis aligned with therotative axis of the crank shaft, the inner end of said torque spring being attached to said crank shaft-and the outer end of said spring being affixed relatively stationary with respect to said casing, a winding knob rotatably supported on said casing and carrying a gear meshing with a companion gear mounted on said crank shaft, a 180 degree locking cam with 180 degree disposed portions thereon mounted on said shaft, a spring pressed dog normally engaging said 180 degree disposed portions on said cam to prevent rotation of said crank shaft, a control cable connected to said dog and extending from said aircraft to move said spring pressed dog out of engagement with said degree disposed portions to allow said crank shaft to rotate, a landing wheel rotatably supported on a strut, said strut being pivoted on said aircraft and means connecting said strut to said crank shaft to move therewith.

6. The invention defined in claim 5 characterized by the incorporation with the structure set forth therein, of a pair of landing flaps pivoted on the aircraft and means connecting said flaps to said shaft to move therewith.

7. In an aircraft control ofthe character described, a source of stored mechanical energy, a.

crank shaft coupled to said source for rotation thereby, a landing wheel movably mounted on said aircraft from a retracted position therein to an extended position and vice versa, said crank shaft being connected to said landing wheel to move the same, an escapement mechanism coupled to said shaft to normally prevent rotation thereof, said escapement mechanism comprising a locking cam having a plurality of abutm'ents thereon, a retractable dog member normally pressed into engagement with one of said abutments, and a control cable extending from said aircraft and attached to said dog member to move said dog member out of engagement with said one abutment.

EDGAR S. COOK.

References Cited in the file of this patent UNITED STATES PATENTS Germany Nov. 17, 1938 

